1. Field of the Invention
The present invention relates to a multi-material, multi-component metal wood golf club head.
2. Description of the Related Art
Golf clubs have achieved a remarkable transformation from persimmon wood clubs to the present day metal woods with their extremely large head sizes. This has been made possible by high strength metallic materials, which allow the golf ball to be hit farther and straighter because of increased club head inertia and coefficient of restitution.
Particularly, development of titanium alloys, which are light (specific gravity: 4.5 to 5.0) and strong, have allowed significant increases in the head size and subsequent practical shaft length of a golf club. Specifically, a large moment of inertia, resulting in an increased area of high speed on the club face can be achieved by use of a large club head. Thus there is a constant demand for club heads of greater size. However, enlarging the club head also increases its weight. Most of the metal wood golf clubs manufactured today have a shell thickness so thin that they border on practical manufacturing limits. This has resulted in the search for materials that are even less dense than titanium. Golf club manufacturers are looking for solutions wherein lighter and stronger materials may be employed. And, in some cases, for materials that will partially replace titanium, which is relatively costly and requires considerable care in forming and casting.
Among the more prominent considerations in club head design are loft, lie, face angle, horizontal face bulge, vertical face roll, center of gravity, inertia, material selection, and overall head weight. While this basic set of criteria is generally the focus of golf club engineering, several other design aspects must also be addressed. The interior design of the club head may be made to achieve particular performance characteristics, such as with the inclusion of hosel or shaft attachment means, or the use of weight members.
The United States Golf Association (USGA), the governing body for the rules of golf in the United States, has specifications for the performance of golf clubs and golf balls. Golf clubs are limited to a Coefficient of Restitution (COR) of 0.83. One USGA rule limits the golf ball's initial velocity after a prescribed impact to 250 feet per second±2% (or 255 feet per second maximum initial velocity). To achieve greater golf ball travel distance, ball velocity after impact and the coefficient of restitution of the ball-club impact must be maximized while remaining within the rules.